Oracle Sun Server X4-4, Service Manual

Page: 26 / 292

Server Subsystems Overview
26 Sun Server X4-4 Service Manual • October 2015
The four-CPU configuration offers a greater level of resiliency with redundant QPI
interconnects that allow working CPUs to route around a disabled CPU as the system starts.
For more information, see “Four-CPU Block Diagram” on page 22 .
Memory Subsystem
The system memory is installed on memory riser (MR) cards. The system requires eight MR
cards for a four-CPU configuration and four MR cards for a two-CPU configuration (Each
processor has two assigned MR cards). MR cards contain twelve DIMM slots, four DDR3
channels, and two memory buffer ASICs. Each memory buffer has two channels (A and B)
and links to three DIMM slots per channel. Each memory buffer is connected to the processor's
built-in memory controller by an SMI-2 link.
For balanced performance, each channel for each memory buffer on the MR card must be
populated. The only exception supported is a minimum orderable configuration of two 16 GB
DIMMs in channel's A and B of memory buffer 0.
For more information about MR cards, and memory layout, including guidelines for populating
cards and DIMMs, see: “Memory Riser Card and DIMM Reference” on page 141
Cooling Subsystem
The internal components in the Sun Server X4-4 are cooled by air that is pulled in through the
front of the server and exhausted out the back of the server. Cooling occurs in two areas of the
chassis, the power supply area and the motherboard area.
Power Supply Cooling Area
The power supply area uses fans at the back of the power supplies to draw cool air in past the
drives, through power supplies, and out the back of the server.
Motherboard Cooling Area
The motherboard area is divided into three zones where six 92-mm high-performance fans
pull cool air in from the front of the server, move it across the motherboard, memory risers,
processors, and I/O cards, and exhausts warm air out the back of the server.
The six fans are arranged in two rows allowing for a pair of stacked fans for each of the three
motherboard zones. The pairing and stacking provides fan redundancy. For example, if one of